Electrical precipitating system



L. w. CHUBB. ELECTRICAL PRECIPITATING SYSTEM.

APPLICATION FILED DEC. 14, I918.

1,433,699. I Patented Oct. 31, 1922.

Lew/ls Warr/h fon C/rubb I a a 5 C BY ATI'ORNEY Patented Oct. 31 1922.

UNITED STATES PATENT OFFICE.

LEWIS WARRINGTON CHUBB, OF PITTSBITRGH, PENNSYLVANIA, ASSIGNOR TO WEST-INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN-SYLVANIA.

Application filed December 14, 1918.

To all whom it may concern:

Be it known that I, LEWIS VVARRING'roN CHUBB, a citizen of the UnitedStates, and a resident of Pittsbur h, in the county of Allegheny andState 0 Pennsylvania, have invented a new and useful Improvement inElectrical Precipitating Systems, of which the following is aspecification.

My invention relates to precipitating systems and particularly tosystems for the precipitation of smoke or other solid particles fromfluid streams, and it has for its object to provide a system of thecharacter designated in which the precipitating opera tion is effectedby the application of a constant current to the precipitating apparatus,irrespective of the internal resistance thereof.

Gases or vapors from which it is desired to precipitate suspendedparticles vary greatly in density, temperature, and other respects whilepassing through the chamber in which the precipitation is to take place.It is a matter of more or less difliculty, therefore, to so applyextremely high voltage to such precipitating chambers that the danger ofa short-circuit between the electrodes which. are positioned therein isentirely and constantly eliminated.

I have discovered that, if a constant current, derived from an extremelyhigh-voltage source, is used to energize the precipitating apparatus, itis of little moment to what degree the temperature, density, and othercharacteristics of the fluid being treated vary. The use of directcurrent in systems of the character designated is especially beneficialwhere a very close control of the precipitating operation is desired,such as must be maintained, for instance, where the particles beingcollected from fluids are of considerable value, as is the case insmelting projects of various types. In systems of the characterdescribed, it is desirable that there be no cessation of theprecipitating operation during the time the particle-laden fluid ispassing through the treating chamber. Such cessation, under normalconditions, will of course, take place when a short-circuit occurs andwhen the high voltage which is so necessary for the production of coronaemission, is dissipated during the interval between the time when such ashort-circuit takes place and the time when the voltage is restored toits desirable high value. During ELECTRICAL PRECIPITATING SYSTEM.

Serial No. 286,744.

this interval, a. great deal of the fluid which it 1s desired to treatmay pass from the stack and the suspended particles therein be whollylost.

rt primary object of my invention is,

therefore, to provide means between the source of power supply and thepoint of application of such power, namely, the precipitatlng apparatus,that will admit of a very high voltage being impressed thereupon andwhich will be instrumental in causing a constant current to be suppliedto the precipitating apparatus, irrespective of fluctuations in thecharacteristics of the treated fluid.

In the accompanying drawing, Fig. 1 illustrates an embodiment of myinvention wherein means are shown upon which a constant voltage isimpressed and from which a constant current is derived; Fig. 2illustrates a modification of the system shown in Fig. 1 in whichrectifying apparatus is utilized to supply the precipitating chamberwith direct current; and Fig. 3 illustrates a further modification ofthe system shown in Figs. 1 and 2, in which a novel manner of supplyingdirect-current voltage of a high value to the precipitating apparatus isshown.

Referring to Fig. 1, a precipitating apparatus 1, comprising acollecting electrode member 2 and a corona-emitting electrode 3, isshown as supplied with power from any suitable source, here shown, forconvenience,

moreover, usually composed of two inductive comes short-circuited andreleases the stored I energy of the reactlve elements of the bridge.

In order to prevent a discharge back through the source, it may bedesirableto place choke-coils, or other current-limitlng devices, in theleads to the source 1, as shown at (S -6.

In Fig. 2, the System shown in Fig. 1

is modified in that a rectifying aggregate 7. comprising, in thisinstance, four hotcathode rectifiers 8, 9, 10 and 11, is interposedbetween the constant-current or independent diagonal of the monocyclicbridge 5 and the precipitating apparatus 1. Each rectifier may comprlsethe usual cathode 15,

to which is connected a battery 16, and a suitable anode 17. Therectifiers are arranged in the four sides of a loop circuit, theconstant current terminals of the monocyclic bridge being connected tooppositely located conductors 18 and 19 between the rectifiers 7 and 10and the rectifiers 9 and 11, respectively. The terminals of thepreeipitatlon circuit are connected to lntermediate points 20 and 21 inthe loop circuit, that is, between the rectifiers 7 and 9 and therectifiers 10 and 11, respectively. An energy-storing and restoringelement, here shown asa condenser 12, is connected between the two sidesof the precipitator circuit,

In Fig. 3, the precipitator 1 is associated with a rectifier-aggregatearrangement con taining the two rectifier elements 8 and 10, in twoadjacent arms thereof and condensive elements 13 and 14 in two otheradjacent arms, the precipitating apparatus or load circuit beingconnected in such manner that the rectifier elements are positioned onone side thereof and the condensive elements on the other side.

The manner in which the rectifying system is employed and claimsspecifically directed thereto are fully set forth in my copendingapplication, Serial Number 167,089,

filed May 7th, 1917, and assigned to the Westinghouse Electric &Manufacturing Company. This application has matured into Patent1,357,223, granted Nov. 2, 1920. I In the conversion or rectification ofalternating current to direct current it is common practice to employ atwo-anode rectifying aggregate, connecting one anode to each terminal ofthe alternating-current source and connecting the cathode tosubstantially the mid-point of'the alternatingcurrent source. By thismeans, both half waves are caused to flow to the direct-cur-- rent loadbut the two halves of the alternating-current source are alternatelyactive, resulting in the uneconomical use of the supply transformer.Furthermore, the theoretical maximum value of the rectified voltage isbut one-half the maximum value of the alternating-current supply.

In accordance with the system set forth in the above-mentioned patent,I'provide a rectifying system in which the entlre transformer supplyvoltage is employed during each half cycle and wherein the maximumvoltage which ma be applied to the load is substantially twice themaximum voltage of the alternating-current supply.

Briefly. summarizing the description of the above-mentioned patent, thisresult is attained by employing auxiliary condensers, charging them tothe voltage of the supply during one-half cycle and discharging themthrough the load, which, in this case, is the precipitator treatingchamber, in series with the supply during the succeeding half cycle,and, in this manner, substantially twice the voltage of the supply isimposed upon the. treating chamber during each half cycle, a resultwhich is. highly beneficial, since the voltage required to cause coronaemission in a precipitating apparatus attains very high values.

Having described a number of systems in which m invention is embodied,the operation thereof is as follows:

Aconstant voltage is impressed upon one diagonal of themonocyclic-bridge arrangement 5, and the precipitating apparatus 1 isconnected to, and derives energy from, the independent or other diagonalof the same devlce. A constant current will, therefore, be supplied tothe apparatus 1 and any tendency for such current to rise, because ofthe existence of unequal temperatures, difv bridge arrangement 5.

The usual form in which my invention is embodied, and probably the onepreferred at the present time for precipitation, is shown in Fig. 2,since the alternating-current method of precipitation is .not at presentapplicable to all classes of work. In this figure, I show directconstant current fed to the apparatus 1 through the instrumentality ofthe bridge apparatus 5 and the rectifying aggregate 7 Since thehotcathode rectifier, in itself forms no part of my present invention,and as the operation thereof is well-known to those skilled in the art,no detailed description of the rectification process is deemed necessaryhere. It is sufficient to note that the alternating current from themonocyclie bridge is rectified in passing through the pairs of illus-'ferent densities, or other reasons existing lrated hot-cathode devices,whereby a sating direct current. is continuously app ied to theterminals 20 and 21 of the precipitator circuit, As a further assuranceof constant operation Iprovide the energystoring and restoring condenser12 which, in this instance, acts as an electrical reserroir.

The particular rectifier arrangement illustrated as associated with theprecipitating apparatus 1 in Fig. 3 is peculiarly adapted to rectifierapplication since, by the use of such apparatus, it is possible toobtain substantially twice the value of the voltage which may beobtained under normal conditions. Moreover, by the particular manner inwhich the arrangement is used in my system this higher voltage isapplied to the precipitator and constant current is fed thereto by theemployment of two rectifier elements only and, since the precipitatoritself functions as a condenser of considerable capacity, the systemdescribed in my patent, above referred to, is of special benefit in theconnection shown.

\Vhile I have shown a number of embodiments of my invention, it isobvious that many modifications therein may occur to.

those skilled in the art and I desire, therefore, that only suchlimitations shall be placed thereupon as are imposed by the prior art orspecifically set forth in the appended claims.

I claim as my invention:

1. In a system of precipitation, the combination with a treatingchamber, of a constant-potential source of power therefor, and meansinterposed therebetween whereby said treating chamber is supplied with aconstant current, irrespective of the re sistance therein.

2. The combination with a precipitating chamber, and a source ofconstant-potential power supply therefor, of a reactive aggregatecomprising reactance elements arranged in a bridge, said source beingconnected to one diagonal of said bridge and said precipitating chamberbeing connected across the other or independent diagonal of said bridge,whereby constant current is supplied to said precipitating chamber,irrespective of the resistance therein.

3. In a system of precipitation, the combination with a. treatingchamber, of a source of alternating-current constant-potential powertherefor, means comprising a bridge composed of reactance elementsinterposed between said chamber and said power source, said source beingconnected across one diagonal of said bridge and said treating chamberbeing connected across the other or independent diagonal thereof, andrectifying means in said last-named circuit, whereby a constant directcurrent is fed to said treating chamber.

4. In a system of precipitation, the combination with a treatingchamber, of a source of alternating-current constant-potential powertherefor, means comprising a bridge composed of reactance elementsinterposed between said chamber and said power source, said source beingconnected across one diagonal of said bridge and said treating chamberbeing connected across the other or independent diagonal thereof,rectifying means in said last-named circuit, whereby a constant directcurrent is fed to said treating chamber, and energy-storing andrestoring means connected in parallel relationship with said treatingchamber.

5. In a system of precipitation, the combination with a treatingchamber, of a source of alternating-current constant-potential supplytherefor, means therebetween whereby said treating chamber is fed with aconstant current, and a rectifier aggregate arranged in a bridge, saidtreating chamber being connected across one diagonal of said bridge,whereby a potential greater than the potential of said source isimpressed upon said treating chamber.

6. In a system of precipitation, the. com- /bination with a treatingchamber, of a source of alternating-current constant-potential supplytherefor, means therebetween whereby said treating chamber is fed with aconstant current, and a rectifier aggregate arranged in a bridge,energy-storing and restoring means in two adiacent arms of said bridge,and rectifying means in the other arms of said bridge, said treatingchamber being connected across one diagonal of said bridge, whereby apotential equal to twice the potential of said source is impressed uponsaid treating chamber.

7. In a system of precipitation, the com bination with a treatingchamber, of a source of alternating-current constant-potential supplytherefor, means therebetween whereby said treating chamber is fed with aconstant current, and a rectifier aggregate arranged in a bridge,energy-storing and restoring means in two adj aceiit arms of saidbridge, and rectifying means in the other arms of said bridge, saidtreating chamber being connected across one diagonal of said bridge,whereby a potential higher than the potential of said source isimpressed upon said treating chamber, with but one-half of therectifying elements normally used in said system.

8. In a system of electrical precipitation, the combination with afluid-treating chamber, of a source of electrical power therefor, andself-regulating means for inherently applying a voltage to said chambersubstantially proportional to the impedance of the discharge paththrough the fluid being treated.

9. Ina system of precipitation, the combination with a treating chamber,of a constant-current source of power therefor, whereby said treatingchamber is suppliedv with constant current, irrespective of the internalimpedance thereof.

10. The method of energizing a precipitation apparatus which consists inapplying a constant current thereto, irrespective of the impedancetherein.

11. The method of energizing a precipitation apparatus in conjunctionwith a constant-potential power source and a bridge device therebetween,which consists in impressing a constant potential upon said device andderivin a constant current therefrom, whereby t e precipitationapparatus is su plied with a constant current, irrespectlve of theresistance therein.

12. The method of electrically precipitating suspended particles fromfluids, which consists in inherently adjusting the value of the voltageimpressed on said fluids substantially in accordance with the impedanceof the dlscharge path through said fluid.

13. The method of electrically precipitating suspended particles fromfluids, which consists in automatically adjusting the value of thevoltage impressed on said fluids substantially in accordance with theimpedance of the discharge path through said fluids.

' 14. The method of electrically precipitating suspended particles fromfluids, which consists in inherently adjusting the value of the voltageimpressed upon said fluids so that it remains just below the breakdownvalue thereof.

15. In a system of precipitation, the combination with a treatingchamber, of a source of alternating-current, a monocyclic bridge havingone set of terminals connected to said source, a rectifier aggregatearranged in a bridge, means for connecting the remaining terminals ofsaid monocyclic bridge to one set of terminals of the rectifier bridgeand means for connecting the remaining terminals of said rectifierbridge to said treating chamber.

16. A system of precipitation comprising a treating chamber, a source ofalternatcurrent of substantially constant potential, a monocyclic bridgehaving one set of terminals connected to said source, a rectifieraggregate arranged in a bridge, energystoring and restoring means beingconnected in two ad'acent arms of the rectifier bridge and recti yingmeans in the other arms of that bridge, means for connecting theremaining terminals of the monocyclic bridge to the terminals of saidrectifier bridge 10' cated between like devices and means for LEWISWARRINGTON CHUBB.

